This invention relates to an engine control and more particularly to a marine engine control that improves running under extremely low speed operating conditions.
In many applications, internal combustion engines are utilized to propel vehicles and are required to run over a wide variety of running speed and load conditions. This presents significant problems in engine design and engine control. That is, the engine design and control can be configured to provide optimum running under some conditions, but then the running of the engine under other conditions will not be satisfactory.
Although computer controls permit a wider range of control capabilities, there are still circumstances where normal engine control strategy is not satisfactory.
A specific example in which engine control is quite difficult is in connection with marine operation. In marine operation, the engine is required many times to operate for fairly extended periods at speeds that are even lower than normal idle speed. This is encountered, for example, when the engine is operated to provide a trolling condition for the watercraft. Under this condition, the engine speed actually is less than idle speed. The reason for this is that the throttle is basically closed and the load on the engine is greater than when operating in neutral. As a result, lower than idle speeds result. At times the trolling speed is significantly lower than idle speed.
Also, there is a problem in ensuring that the engine continues to run for long periods under these trolling speeds. Stalling is a common problem in connection with trolling operations.
It is, therefore, a principal object of this invention to provide an improved engine control for arrangements where the engine operates under very low speeds and for extended periods.
It is a further object of this invention to provide an improved trolling engine control for a marine engine.
In conjunction with the operation at trolling or less than idle speeds, the engine may frequently be associated with a transmission and the transmission may be shifted from neutral to either a forward or reverse drive condition. When this occurs, the load on the engine significantly increases when the clutch is engaged and stalling can occur.
These problems may be somewhat compounded when shift controls are employed that provide an automatic speed reduction, for example, by cylinder disabling, when shifting from neutral to a drive condition. This type of engine speed reduction is utilized to facilitate shifting and to minimize loading on the transmission. However, it still further increases the likelihood of stalling.
It is, therefore, a further object of this invention to provide an improved marine engine control utilizing a transmission and wherein stalling under extreme low speed and shifting conditions will be avoided while shifting can still be facilitated.